port questions

[atlninja82 10+ year member]

hey guys i got a couple questions. im building a box for an FI BL and the site recomends 12-16 inches of port area per ft^3 and the box im using is 2.03 before displacements. after it will probably be around 1.75-1.8 ft^3. my question is how do i calculate port area? im using a slotted port so woud i just multiply the dimensions of the port 12 long x 2.5 wide? and i get 30 sq inches of port area?

2nd question- ive used a lot of port calculators and one told me only 6 inches of port length to tune at 36 hz which i know cant be right. but then i used a few others and they said anywhere from 28-32 inches. why is it so long? can i increase the port area so the port doesnt have to be so long?

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[skmfkr 5,000+ posts]

more port area = more port length to get the same tuning and yeh 1.8cf 30 square inches of port area and 36hz tuning is like 29" long

 

[bubbagumper6 5,000+ posts]

1st question = yes that's correct

2nd question = what calculators are you using? the12volt.com and winisd are both good

 

[atlninja82 10+ year member]

i have winisd but i cant figure out how to use it. so i used mobileinformationlabs.com.